SusChEM: Controls on struvite neogenesis and reactivity in engineered and geochemical systems

技术描述磷（P）可以从人类和农业废物中以矿物鸟粪石（MgNH 4PO 4·6 H2O）的形式回收，可用作传统肥料的替代品。本项目探讨了鸟粪石从不同类型废物中产生时的性质和反应性，并与地球化学产生的鸟粪石进行了比较。研究的目标是阐明支配鸟粪石的物理和化学性质的总体条件和参数，独立于新生的来源。鸟粪石将从养猪场废水、温室废水和莫诺湖水中沉淀出来。动物和植物废物通常用于鸟粪石回收的工程系统中，而莫诺湖是一个具有鸟粪石历史存在的地球化学系统。将使用以去离子水作为溶剂的模型溶液来确定具体的控制;即pH值、离子强度、溶解的有机物;对所得矿物性质的影响。还将评估起始溶液中普遍存在的痕量污染物（如金属）的吸附。这是特别关键的，因为鸟粪石性质对吸附过程的影响尚未事先确定，相反，吸附的杂质对矿物结构和稳定性的影响是未知的。本研究将采用PXAFS、~（31）P NMR、~（33）P放射性示踪剂和TG/DSC-FT-IR等先进和创新的技术，这些技术可用于其他磷酸盐矿物的研究。从这项研究的结果可以用来操纵鸟粪石在工程系统中的性能，取决于废物成分和实施条件。从废物中更好地设计鸟粪石的能力将促进鸟粪石肥料的使用，并鼓励可持续地使用磷。这是因为磷是一种有限的自然资源，由于其用作肥料，人类活动加速了其循环。随着磷地质储量的减少和全球人口的不断增加，人类循环中损失的磷需要得到补偿。这可以通过从人类和农业废物中回收磷作为磷酸盐矿物鸟粪石来实现。 使用回收鸟粪石作为替代肥料来源将促进磷的可持续利用，保护天然磷资源，并限制释放额外的磷螯合在岩石中的人类循环。该项目将使人们更好地了解鸟粪石的物理和化学特性，鸟粪石是从各种来源产生的，包括动物和植物废物。结果可用于预测，并可能控制，回收鸟粪石的性质和污染物含量的废水组成和回收条件的基础上。这提供了安全性，即鸟粪石作为肥料输送到土壤中，可以按要求发挥作用，不会造成污染风险，因此不会对土壤、农业生态系统和地球化学系统造成环境责任。最终，从废物中回收的鸟粪石作为磷的来源的再利用将通过提供替代的可持续肥料来养活不断增长的全球人口，从而为人类磷循环带来可持续性。

Technical DescriptionPhosphorus (P) can be recovered from human and agricultural wastes as the mineral struvite (MgNH4PO4·6H2O), which can be used as an alternative to traditional fertilizers. This project addresses the properties and reactivity of struvite when generated from different types of wastes, and as compared to geochemically produced struvite. The goal of the research is to elucidate the overarching conditions and parameters that dictate the physical and chemical properties of struvite, independent of source of neogenesis. Struvite will be precipitated from swine effluent, greenhouse wastewater, and Mono Lake water. The animal and plant wastes are commonly used in engineered systems for struvite recovery, and Mono Lake is a geochemical system with a historical occurrence of struvite. Model solutions, with deionized water as the solvent, will be used to determine the specific controls; i.e. pH, ionic strength, dissolved organics; on the resultant mineral properties. The sorption of trace contaminants such as metals, prevalent in starting solutions, will also be assessed. This is particularly critical because the impact of struvite properties on sorption processes has not been previously determined, and conversely the effect of sorbed impurities on the mineral structure and stability are not known. The research will implement several advanced and innovative techniques, including P XAFS, 31P NMR, 33P radiotracers and TG/DSC-FT-IR, which are transferable to the study of other phosphate minerals. Results from this research can be used to manipulate the properties of struvite in engineered systems, contingent upon waste composition and implemented conditions. The ability to better engineer struvite from wastes will advance the use of struvite fertilizers and encourage the sustainable use of P.Importance for SocietyThe human phosphorus (P) cycle is unsustainable. This is because P is a limited natural resource, the cycling of which is accelerated by human activity due to its use as fertilizer. With diminishing geologic P reserves, and an ever increasing global population, P lost in the human cycle needs to be recouped. This can be achieved by the recovery of P from human and agricultural wastes as the phosphate mineral struvite. The use of recovered struvite as an alternative fertilizer source will promote the sustainable use of P, conserve natural P resources, and limit the release of additional P sequestered in rocks to the human cycle. This project will provide an improved understanding of the physical and chemical properties of struvite when generated from a variety of sources, including animal and plant wastes. Results can be used to predict, and potentially control, the properties and contaminant content of recovered struvite based on wastewater composition and recovery conditions. This provides the security that struvite delivered to soils as fertilizer can function as required and does not pose a contamination risk, and thus an environmental liability to soils, agro-ecosystems and geochemical systems. Ultimately, the reuse of struvite recovered from wastes as a source of P will introduce sustainability to the human P cycle by providing an alternative, sustainable fertilizer to feed a growing global population.